It is solved a problem of construction of separately continuous functions on
the product of compacts with a given discontinuity points set. We obtaine the
following results.
- For arbitrary \v{C}ech complete spaces X, Y and a separable compact
perfect projectively nowhere dense zero set E⊆X×Y there exists
a separately continuous function f:X×Y→R the discontinuity
points set of which equals to E.
- For arbitrary \v{C}ech complete spaces X, Y and nowhere dense zero
sets A⊆X and B⊆Y there exists a separately continuous
function f:X×Y→R such that the projections of the
discontinuity points set of f coincide with A and B respectively.
An example of Eberlein compacts X, Y and nowhere dense zero sets
A⊆X and B⊆Y such that the discontinuity points set of
every separately continuous function f:X×Y→R does not
coincide with A×B, and CH-example of separable Valdivia compacts X,
Y and separable nowhere dense zero sets A⊆X and B⊆Y
such that the discontinuity points set of every separately continuous function
f:X×Y→R does not coincide with A×B are constructed.